Galena

Galena (PbS)

One of the Sulphide group of minerals, is the
principle ore from which lead, and to a lesser degree silver, is optained.
It's distribution is pretty much world-wide and can usually be found in
association with Fluorite (used as a flux in steel manufacturing)
and Sphalerite (ZnS) the principle zinc ore.

Uses of Galena.
It was once used in early Crystal radio sets and was the original "cat's
whisker" in combination with a phosphor-bronze wire, which formed the
point-contact diode necessary for early wireless reception (later
superceded by Germanium and Silicon for diode materials).
The 'point contact' effect action was first discovererd in 1906. The
construction and operation of the Cat's Whisker seems quite archaic
compared to modern day silico diodes. The Galena crystal, normally
untreated as-mined and about the size of a pea in size, was mounted
in a brass cup. The exposed surface was then probed by a piece of thin
phosphor-bronze until a satisfactory contact was made. Patience and
not a little skill was required to find the correct spot for good reception,
which was often spoiled by even the slightest knock or vibration,
requiring further tedious 're-tuning'. Many boys' annuals, like 'The Boy's
Own Paper' at the turn of the 20th Century, regularly featured DIY crystal
set plans, based around the Cat's Whisker which have been the
inspiration of many a subsequent career in radio and electronics.

Extraction of Lead and Smelting.
Galena has been mined in Britain from as far back as the Roman times. In
the Derbyshire Peak District, England, the Galena or Lead Sulphide was
at first manually crushed with a hammer but later more efficient
mechanical methods were introduced in the 18th & 19th centuries.
Running water was used to serparate the various minerals of differing
densities, after crushing. The remains of abandoned mine shafts,
crushing circles and water channels for mineral serparation can still be
seen to this day over the Derbyshire hills.

Early smelting was a rather primitive affair, with an open sloping stone
hearth alternatively stacked with wood and ore set alight. When a high
enough temperature was reached to break the chemical bonds of the
Galena, molten ore flowed with sulphur as a by-product, amongst
others. Later, bellows together with enclosed hearths, made the smelting
process much more efficient.

Although lead mining is now defunct in the UK, the keen eyed trekker can
still come across the occasional piece of Galena ore, glinting in the
sunshine, a small remnant of an industry which, for nearly two thousand
years, kept the building, plumbing, paint, battery and many other
industries fed with raw material. But, these industries probably pale into
insignificance when compared to the amount of lead used in the arms industry!

Buying Rocks and Minerals Online

To Sitemap from Galena

How are minerals formed.